/*
 * linux/fs/nls_koi8-ru.c
 *
 * Charset koi8-ru translation based on charset koi8-u.
 * The Unicode to charset table has only exact mappings.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/nls.h>
#include <linux/errno.h>

static struct nls_table *p_nls;

static int uni2char(const wchar_t uni,
                    unsigned char *out, int boundlen)
{
    if (boundlen <= 0)
        return -ENAMETOOLONG;

    if ((uni & 0xffaf) == 0x040e || (uni & 0xffce) == 0x254c) {
        /* koi8-ru and koi8-u differ only on two characters */
        if (uni == 0x040e)
            out[0] = 0xbe;
        else if (uni == 0x045e)
            out[0] = 0xae;
        else if (uni == 0x255d || uni == 0x256c)
            return 0;
        else
            return p_nls->uni2char(uni, out, boundlen);
        return 1;
    }
    else
        /* fast path */
        return p_nls->uni2char(uni, out, boundlen);
}

static int char2uni(const unsigned char *rawstring, int boundlen,
                    wchar_t *uni)
{
    int n;

    if ((*rawstring & 0xef) != 0xae) {
        /* koi8-ru and koi8-u differ only on two characters */
        *uni = (*rawstring & 0x10) ? 0x040e : 0x045e;
        return 1;
    }

    n = p_nls->char2uni(rawstring, boundlen, uni);
    return n;
}

static struct nls_table table = {
    /* .charset */ "koi8-ru",
    /* .alias */   0,
    /* .uni2char */ uni2char,
    /* .char2uni */ char2uni,
    0, 0,
    /* .owner */ THIS_MODULE,
};

static int __init init_nls_koi8_ru(void)
{
    p_nls = load_nls("koi8-u");

    if (p_nls) {
        table.charset2upper = p_nls->charset2upper;
        table.charset2lower = p_nls->charset2lower;
        return register_nls(&table);
    }

    return -EINVAL;
}

static void __exit exit_nls_koi8_ru(void)
{
    unregister_nls(&table);
    unload_nls(p_nls);
}

module_init(init_nls_koi8_ru)
module_exit(exit_nls_koi8_ru)

MODULE_LICENSE("Dual BSD/GPL");
